Remove os-testr from requirements

keystoneauth is switched to stestr, we don't need to depend on os-testr
anymore.

Change-Id: Ie3fc5e5b03f5c0865bf3f499666f504703cd0b0d

lower-constraints.txt

@@ -38,7 +38,6 @@ openstack-requirements==1.2.0
 openstackdocstheme==1.18.1
 os-client-config==1.29.0
 os-service-types==1.2.0
-os-testr==1.0.0
 oslo.config==5.2.0
 oslo.i18n==3.20.0
 oslo.utils==3.33.0

test-requirements.txt

@@ -14,7 +14,6 @@ oslo.config>=5.2.0 # Apache-2.0
 openstackdocstheme>=1.18.1 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
-os-testr>=1.0.0 # Apache-2.0
 betamax>=0.7.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 requests-mock>=1.2.0 # Apache-2.0